Safety lid for pressure tank



April 23, 1963 c. w. CLARK, JR

SAFETY LID FOR PRESSURE TANK Filed Sept. 21, 1959 INVENTOR. CHARLES WILLIAM GLARKJ.

ATTORNEYS United States atent 3,086,675 SAFETY LID FOR PRESSURE TANK Charles W. Clark, Jr., Edmonds, Wash, assignor to Sweden Freezer Manufacturing Co., Seattle, Wash, a corporation of Washington Filed Sept. 21, 1959, Ser. No. 841,078 2 Claims. (Cl. 220-245) This invention relates to pressure tanks with lids of the type in which the lid is sealed with a compression ring which can be compressed into sealing relation to the tank inadvertently without first turning the lid into a locked position. A principal object of the invention is to provide a safety arrangement whereby such a lid cannot be sealed until the lid has been initially turned at least to a safety position whereat it cannot fly off responsive to introduction of pressure fluid to the tank. A further object is to provide a lid which acts automatically in response to its removal from the tank to bleed ofi the pressure in a manner which introduces no hazard to the operator.

These and other more particular objects and advantages will appear and be understood in the course of the following description and claims. The invention consists in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawing:

FIGURE '1 is a fragmentary top plan view representing a pressure tank and lid assembly constructed to embody the preferred teachings of the present invention.

FIG. 2 is a fragmentary vertical sectional view thereof on line 2-2 of FIG. 1; and

FIGS. 3 and 4 are detail fragmentary views in side elevation taken from the vantage point represented by 33 in FIG. 2 and illustrating the lid in two stages of its removal operation.

Referring to said drawing, the numeral 5 designates a pressure tank serving as a receptacle for any desired fluid substance as, for example, a syrup arranged to be dispensed under the influence of carbon dioxide or other suitable pressure agent. Neither the opening through which said substance is dispensed nor the means by which the tank is pressurized are shown in the drawing. The safety lid to which the present invention pertains fits over a neck 6 defining a large-mouth opening through which the substance is introduced to the tank and which also facilitates cleaning of the tank when the contents have been exhausted.

The lid has a cap-piece which is arranged to fit over said neck, this cap-piece presenting a crown section 8 skirted by a flange 10. The flange is provided with a plurality, three being shown, of re-entrant slots 11 located at equidistantly spaced intervals of the circumference. =12 designates bayonet-stud complements of the slots fixed to the neck so as to register with the slots. The slots are inclined at rather a moderate angle, say 30, from the plane occupied by the bottom edge of the flange, and two notches, or steps as they will be hereinafter termed, are provided in the sloping bottom wall of each slot. The bayonet studs admit of being seated upon either the upper-level step 13 or the lower-level step 14, and each said step has a terminal prominence, as 15 and 16, which guards the bayonet studs against becoming accidentally dislodged from the steps. Whereas each npper-level prominence :15 has very little rise so that the lid need be depressed in only a minor degree, relative to the neck, in order to slip the stud ofl the step 13, each lower-level prominence 16 is quite pronounced and is furthermore very abrupt, hence necessitates a substantial degree of relative endwise motion to unseat the stud.

As complements of the cap-piece, the invention provides an O-ring seal 17 of neoprene or other like or suitable material having a normal unstressed compass, O.D. considered, closely approximating the inside diameter of the neck 6. This O-ring is received between rim flanges 20 and 21 of two correspondingly dished annular plates 22 and 23, respectively, which depend by a liftrod 24 from the cap-piece one above the other immediately below the crown. The dishing of the plates is such as to produce a wall 25 disposed in backing relation to the O-ring, thus forcing the material of the O-ring outwardly upon being compressed between the plates. The upper of the two rim flanges, and namely the rim flange 20, is adapted upon application of the lid to the pressure tank to occupy a position spaced somewhat above the neck 6 and bearing against the underside of the cappieces crown section 8. The diameter (thickness) of the material composing the O-ring is such that the other rim flange 21 occupies a position within the neck spaced somewhat below the upper limit thereof. The outside diameter of such flange 21 is perforce less than the inside diameter of the neck.

Said rod 24 has a pressure-tight connection with the lower plate 23, and slides freely through central apertures provided in the upper plate 22 and the crown section 8 of the cap-piece. A block 26 is fixedly attached to a protruding upper end of such pin. This block fits in the slot 27 provided by a forked lever 28 and is pivoted to the fork-arms of the latter by a traversing pin 30. The lever has a cam face 31. When located in the position in which it is shown, said cam face operates to raise the block 26 from a normal inactive position resting upon the crown-section, thereby lifting the plate 23 to responsively compress the O-ring. The compressed O-ring is squeezed outwardly against the neck 6, which seals the tank against escape of compressed gas introduced thereto.

Reverting to the bayonet slots it should be stressed that the recited slope of an approximate 30 is provided in the upper wall as well as, generally, in the notched bottom wall. The upper said slope is uninterrupted and at its upper limit extends inwardly somewhat beyond a perpendicular raised from the stop-shoulder presented by the prominence 16. The span between said upper slope and the prominence only slightly exceeds the diameter of the studs 12.

When applying the lid to the tank the rather heavy weight of the lid causes the studs to ride up the sloping upper wall so that, even should an operator inadvertently fail to twist the lid in order to fix the bayonet joints, the lid turns itself in a degree sufficient to position the studs above the lower-level step '14. If pressure is now prematurely supplied to the tank, there is no danger of the lid flying free in that the studs lodge behind the abutment shoulders of the prominences 16. A pressure-tight application of the lid is perforce accomplished by lodging the studs on the upper-level steps 13 and then pushing the handle of the lever 28 downwardly to locate the cam face 31 in the position in which it is shown in FIG. 2. When removing the lid the procedure is to first swing the lever 28 upwardly so that the cam face 31 is made inactive. The plate 23 is thereby freed of lift originating in the lever but is perforce still forced upwardly by any pressure condition existing within the tank. By now giving the cap-piece a moderate turn in a counterclockwise direction, the operator permits gasses to escape as the cap-piece rises, this rise, however, being only in the minor degree described by the vertical spacing between the two steps 13 and 14. The abrupt and relatively high abutments 16 of said lower-level steps securely lock the bayonet studs 12 against further travel until the compressed gasses have become substantially dissipated, whereupon the cap-piece may be fully removed with com plete safety. It should be noted that the distance from the roof of each slot, axially of the tank, and directly above the respective prominence 16, to the center of the O-ring 17 when the latter is compressed by action of the lever 28, is greater than the axial distance'from the top of the studs 12 to the upper rim of the neck 6. This precludes the O-ring from being accidently deformed into sealing relation with the neck '6 until the lid is turned into at least the safety position above the lower seat 14 either by action of gravity as before mentioned, or manually, as well as insuring venting of the tank before the lid can be manually turned in the counter direction such as to move the studs 12 beyond the prominences 16.

It is believed that the invention will have been clearly understood from the foregoing detailed description of the illustrated preferred embodiment. Minor changes will suggest themselves and may be resorted to without departing from the spirit of the invention, wherefore it is intended that no limitations be implied and that the {hereto annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What I claim, is:

1. In combination with a pressure tank providing an 7 access opening surrounded by a protruding annular neck and having a plurality of bayonet studs extending radially from said neck at spaced intervals of the circumference, a safety lid therefor providing a-cap-piece comprised of a centrally apertured crown section arranged to overlie the opening and having a skirt section which fits over the neck, said skirt section having slot complements of said bayonet studs formed therein and each characterized in that the lower edge thereof is stepped to provide an upper-level and a lower-level seatfor -the respective stud spaced apart both axially and circumferentially of the cappiece, said lower-level seat presenting a terminal prominence locking the stud against accidental dislodgement from the seat, said prominence being axially spaced beneath the upper edge of the slot a distance only slightly greater than the respective diameter of the stud, an expandable sealing ring carried-by the cap-piece so as to underlie the crown section thereof and characterized in that the same is made eifective to produce a pressure seal between the rim of the neck and the cap-piece upon being subjected to a flattening deformation under force of compression pressure exerted upon the ring in a direction endwise to its axis, and compression means operative independently ofturning of said cap-piece relative to said tank and carried by said cap-piece for exerting said compression pressure upon the sealing ring, the axial distance from the upper edge of each said slot at a point directly above the respective prominence tothe center of the sealing ring when the ring is compressed by said compression means being greater than the axial distance from the top of the studs to the upper rim of the tank neck whereby said sealing ring cannot be deformed into seal ing relation with said neck until'said cap-piece is turned such as to advance said studs in said slots toward said upper-level seat beyond said prominences and whereby said cap piece cannot be turned in the counter direction beyond said lower-level seat without unsealing said ring.

2. The combination of claim 1 in which the upper edge of each said slot is sloped upwardly from the bottom of said skirt section whereby said lid tends to turn by force ofgravity on said studs to a position wherein said lower-levelseats underlie the studs.

References Cited in thefile of this patent UNITED STATES PATENTS 1,939,569 Pfister Dec. 12, 1933 2,191,614 Frantz Feb. 27, 1940 2,779,515 Welty Jan. 29, 1957 FOREIGN PATENTS 21,935 Switzerland July 28, 1900 333,400 Great Britain Aug. 14, 1930 158,497 Austria Aug. 26, 1954 wcn 

1. IN COMBINATION WITH A PRESSURE TANK PROVIDING AN ACCESS OPENING SURROUNDED BY A PROTRUDING ANNULAR NECK AND HAVING A PLURALITY OF BAYONET STUDS EXTENDING RADIALLY FROM SAID NECK AT SPACED INTERVALS OF THE CIRCUMFERENCE, A SAFETY LID THEREFOR PROVIDING A CAP-PIECE COMPRISED OF A CENTRALLY APERTURED CROWN SECTION ARRANGED TO OVERLIE THE OPENING AND HAVING A SKIRT SECTION WHICH FITS OVER THE NECK, SAID SKIRT SECTION HAVING SLOT COMPLEMENTS OF SAID BAYONET STUDS FORMED THEREIN AND EACH CHARACTERIZED IN THAT THE LOWER EDGE THEREOF IS STEPPED TO PROVIDE AN UPPER-LEVEL AND A LOWER-LEVEL SEAT FOR THE RESPECTIVE STUD SPACED APART BOTH AXIALLY AND CIRCUMFERENTIALLY OF THE CAPPIECE, SAID LOWER-LEVEL SEAT PRESENTING A TERMINAL PROMINENCE LOCKING THE STUD AGAINST ACCIDENTAL DISLODGEMENT FROM THE SEAT, SAID PROMINENCE BEING AXIALLY SPACED BENEATH THE UPPER EDGE OF THE SLOT A DISTANCE ONLY SLIGHTLY GREATER THAN THE RESPECTIVE DIAMETER OF THE STUD, AN EXPANDABLE SEALING RING CARRIED BY THE CAP-PIECE SO AS TO UNDERLIE THE CROWN SECTION THEREOF AND CHARACTERIZED IN THAT THE SAME IS MADE EFFECTIVE TO PRODUCE A PRESSURE SEAL BETWEEN THE RIM OF THE NECK AND THE CAP-PIECE UPON BEING SUBJECTED TO A FLATTENING DEFORMATION UNDER FORCE OF COMPRESSION PRESSURE EXERTED UPON THE RING IN A DIRECTION ENDWISE TO ITS AXIS, AND COMPRESSION MEANS OPERATIVE INDEPENDENTLY OF TURNING OF SAID CAP-PIECE RELATIVE TO SAID TANK AND CARRIED BY SAID CAP-PIECE FOR EXERTING SAID COMPRESSION PRESSURE UPON THE SEALING RING, THE AXIAL DISTANCE FROM THE UPPER EDGE OF EACH SAID SLOT AT A POINT DIRECTLY ABOVE THE RESPECTIVE PROMINENCE TO THE CENTER OF THE SEALING RING WHEN THE RING IS COMPRESSED BY SAID COMPRESSION MEANS BEING GREATER THAN THE AXIAL DISTANCE FROM THE TOP OF THE STUDS TO THE UPPER RIM OF THE TANK NECK WHEREBY SAID SEALING RING CANNOT BE DEFORMED INTO SEALING RELATION WITH SAID NECK UNTIL SAID CAP-PIECE IS TURNED SUCH AS TO ADVANCE SAID STUDS IN SAID SLOTS TOWARD SAID UPPER-LEVEL SEAT BEYOND SAID PROMINENCES AND WHEREBY SAID CAP-PIECE CANNOT BE TURNED IN THE COUNTER DIRECTION BEYOND SAID LOWER-LEVEL SEAT WITHOUT UNSEALING SAID RING. 